1. Field of the Invention
The present invention generally relates to vehicle control circuits and, more particularly, to apparatus for controlling the termination of direction turn signals.
2. Prior Art
With the increased mobility of the world's population due to vehicular travel, it has become evident that advances are necessary to provide for improved vehicle safety features. In particular, the need to provide improved directional signal control apparatus for vehicles in general, and motorcycles specifically, is of prime importance. Although the present invention is equally applicable to automobiles and like vehicles which employ rotating steering columns which can easily employ directional signal shafts, the present invention will be discussed in terms of its primary application for motor driven cycles which shall be understood to include motorcycles, mopeds, motor scooters, etc. The latter types of vehicles are unique in the sense that there is no full rotation of the steering mechanism to execute a lane change or turn, but to the contrary, such changes in directions are often, if not always, accomplished through the use of weight allocation. The result of the change in weight allocation will cause a deflection of the motor driven cycle from its quiescent vertical oreintation with little movement of the handlebar and coupled steering column.
The prior art discloses several rudamentary types of devices which are used to control the duration of the directional signal used on the motor driven cycle. The simplest of these devices is merely a manual switch operated by the user to indicate the start and stop of a left or right hand lane change or turn. Other types of simple devices are based solely on time and distance. The operator of the motor driven cycle initiates a manual switching mechanism to start the directional flashers. The detectors which combine input signals based on time and distance will reset the directional signal irrespective of the dynamics of the operation of the motor driven cycle. The inadequacies of these devices are obvious. The elementary manual switches are clearly deficient since the operator can totally neglect to reset the switches after he has completed the lane change or turn. With respect to the circuit based on time and distance, since there is no input which is based on the actual dynamics of the motor driven cycle, the directional signals can be reset even though the operator has not completed and possibly has not even started the lane change or turn.
There are a number of devices disclosed by the prior art which seek to automatically cancel a turn signal by monitoring specific aspects of the vehicle's operation. In U.S. Pat. No. 4,125,827, the self-cancelling turn signal apparatus operates in response to an upshift of the transmission. It is clear that although a turn may occur within an appropriate time interval encompassing a change in gears, there is no assurance that such combination will occur. U.S. Pat No. 4,030,066 discloses a self-cancelling turn signal which is controlled by a gyroscope. This device utilizes the precession movement of the gyroscope and, in particular, the return movement of same. It is therefore clear that it is a change in direction which is the operative input to this device, an input which can be defective as a result of the actual dynamics of the cycle. U.S. Pat. No. 3,876,976 discloses a self-cancelling apparatus for cycles which is responsive to changes in the gravitational and inertial forces experienced by the vehicle due to inclination from its normally upright position or due to its change in direction. As with the other devices disclosed by the prior art, this device does not fully accomplish its intended purpose since the dynamics of the cycle can produce inputs which would cancel the vehicle turn indicator signal despite the fact that the turn has not in fact been completed and may not have even been started.
The present invention substantially resolves the problems which are inherent in the devices disclosed in the prior art. The present invention detects small changes in the turn angle of the steering wheel as well as producing signals which are responsive to the velocity of the cycle as well as the distance being traveled. In operation, a cycle can make a 90.degree. turn with only small deflections in the turn angle of the steering column. In addition, the cycle operator may change lanes prior to making the actual turn and, in fact, stop the cycle totally prior to making a turn but after the turn indicator is activated. The present invention generates a signal responsive to a change in the rotational angle of the steering column. When the operator has initiated a manual vehicle turn signal which corresponds to the detected change in the steering angle, a signal is generated which is responsive to the turn, the initiation of the signal starting the commencement of the cancellation cycle. In order to appropriately deal with the dynamics of the cycle, a signal responsive to the distance being traveled by the cycle is generated. The signal responsive to the distance traveled must exist for a sufficient interval to insure that an inadvertent cancellation signal is not produced. When the time interval has been met, the output of a digital counter will turn on a bistable element to initiate a cancellation signal. In addition, to avoid an inadvertent cancellation signal during that period of time when the cycle is halted, the counter will not be permitted to advance in the absence of signals responsive to minimum distance traveled and the rate thereof, i.e., velocity. It can therefore be seen that the inadequacies of the devices disclosed by the prior art are solved by the present invention.